While the Iron Curtain was still in place under the communist government, Prague was 29 visited by foreigners.
答案：(B) seldom
語意「布拉格很少被外國人造訪」（共產政權鐵幕時期），seldom（很少）符合這種封閉歷史背景；ever（通常用於疑問/否定句）、nearly（幾乎，「幾乎被造訪」語意奇怪）、wholly（完全地）都不合。
seldom 你背過的中文是「很少」，但它其實是否定副詞，一填進 was ______ visited 這個位置，整句的意思就從「被造訪」翻成「幾乎沒被造訪」。沒有把它當否定看的人，往往就在四個副詞之間憑語感亂猜。
兩條線索，一條在句構，一條在上下文。句構上，空格夾在 be 動詞 was 與過去分詞 visited 之間，這正是頻率副詞的標準位置——你國中背過 He is always late.、He seldom goes out.，規則就是放在 be 動詞後面、一般動詞前面（劍橋 English Grammar Today 的 adverb position）；四個選項裡只有 seldom 是頻率副詞，光靠位置就能定案。上下文上，前面說 While the Iron Curtain was still in place under the communist government（在共產政權統治、鐵幕仍未拆除的時期），封閉的年代自然少有外國人造訪；再看下一句 Since the 1990s, however, all that has changed（但自從 1990 年代起，那一切都改變了）——既然「改變了」，之前的狀態必然與現在的觀光盛況相反。前後夾擊，答案只剩 seldom。
ever：多用在疑問句、否定句、比較句或完成式裡（Have you ever been there?），單獨放在肯定的敘述句中不成立。nearly（幾乎）：修飾的是「接近某個程度或數量」，「幾乎被造訪」不成話；nearly 該用在 nearly untouched（幾乎未受破壞）這種地方，本文第三句就有一個現成的例子可以對照。wholly（完全地）：意思是「徹底地、整個地」，與 visited 搭不起來，方向也與上下文相反。
seldom（很少、幾乎不）、rarely（罕有地）、be visited by（被……造訪）、the Iron Curtain（鐵幕）、be in place（就位、實施中）、under the communist government（在共產政權統治下）。
Prague, the capital of the Czech Republic, is a very beautiful city. Situated on both banks of the winding River Vltava, Prague is like one big open-air museum. 26 some six hundred years of architecture nearly untouched by natural disaster or war, the city retains much of its medieval appearance. 27 you go, there are buildings in Romanic, Baroque, and Rococo styles that were popular hundreds of years ago. All of them successfully 28 the destruction of postwar redevelopment and remained unchanged.
While the Iron Curtain was still in place under the communist government, Prague was 29 visited by foreigners. Since the 1990s, 30 , all that has changed. Prague is now one of the most popular tourist attractions in Europe.